High strength titanium alloys

Abstract

A non-limiting embodiment of a titanium alloy comprises, in weight percentages based on total alloy weight: 2.0 to 5.0 aluminum; 3.0 to 8.0 tin; 1.0 to 5.0 zirconium; 0 to a total of 16.0 of one or more elements selected from the group consisting of oxygen, vanadium, molybdenum, niobium, chromium, iron, copper, nitrogen, and carbon; titanium; and impurities. A non-limiting embodiment of the titanium alloy comprises an intentional addition of tin and zirconium in conjunction with certain other alloying additions such as aluminum, oxygen, vanadium, molybdenum, niobium, and iron, to stabilize the α phase and increase the volume fraction of the α phase without the risk of forming embrittling phases, which was observed to increase room temperature tensile strength while maintaining ductility.

We claim: 
     
       1. A titanium alloy comprising, in weight percentages based on total alloy weight:
 2.0 to 5.0 aluminum; 
 greater than 3.0 to 8.0 tin; 
 1.0 to 5.0 zirconium; 
 6.0 to 12.0 of one or more elements selected from the group consisting of vanadium and niobium; 
 0.1 to 5.0 molybdenum; 
 0.01 to 0.40 iron; 
 0.005 to 0.3 oxygen; 
 0.001 to 0.07 carbon; 
 0.001 to 0.03 nitrogen; 
 optionally, one or more of chromium and copper, wherein the total content of oxygen, vanadium, molybdenum, niobium, chromium, iron, copper, nitrogen, and carbon is no greater than 16.0; 
 titanium; and 
 impurities. 
 
     
     
       2. The titanium alloy of  claim 1 , wherein the titanium alloy comprises an aluminum equivalent value of 6.0 to 9.0. 
     
     
       3. The titanium alloy of  claim 1 , wherein the titanium alloy comprises a molybdenum equivalent value of 5.0 to 10.0. 
     
     
       4. The titanium alloy of  claim 1 , wherein the titanium alloy comprises an aluminum equivalent value of 6.0 to 9.0 and a molybdenum equivalent value of 5.0 to 10.0. 
     
     
       5. The titanium alloy of  claim 1 , wherein a sum of aluminum, tin, and zirconium contents is, in weight percentages based on the total alloy weight, 8 to 15. 
     
     
       6. The titanium alloy of  claim 1 , wherein a ratio of the aluminum equivalent value to the molybdenum equivalent value is 0.6 to 1.3. 
     
     
       7. The titanium alloy of  claim 1 , wherein the titanium alloy exhibits an ultimate tensile strength (UTS) of at least 170 ksi at room temperature, and wherein the ultimate tensile strength and an elongation of the titanium alloy satisfy the equation:
   (7.5×Elongation in %)+UTS≥260.5.
 
 
     
     
       8. A method of making a titanium alloy, the method comprising:
 solution treating a titanium alloy at 760° C. to 840° C. for 1 to 4 hours; 
 air cooling the titanium alloy to ambient temperature; 
 aging the titanium alloy at 482° C. to 593° C. for 8 to 16 hours; and 
 air cooling the titanium alloy, 
 wherein the titanium alloy has the composition recited in  claim 1 . 
 
     
     
       9. A titanium alloy comprising, in weight percentages based on total alloy weight:
 8.6 to 11.4 of one or more elements selected from the group consisting of vanadium and niobium; 
 4.6 to 7.4 tin; 
 2.0 to 3.9 aluminum; 
 1.0 to 3.0 molybdenum; 
 1.6 to 3.4 zirconium; 
 0 to 0.5 chromium; 
 0 to 0.4 iron; 
 0 to 0.25 oxygen; 
 0 to 0.05 nitrogen; 
 0.001 to 0.07 carbon; 
 titanium; and 
 impurities. 
 
     
     
       10. The titanium alloy of  claim 9  comprising, in weight percentages based on total alloy weight:
 8.6 to 9.4 of one or more elements selected from the group consisting of vanadium and niobium. 
 
     
     
       11. The titanium alloy of  claim 9  comprising, in weight percentages based on total alloy weight:
 10.6 to 11.4 of one or more elements selected from the group consisting of vanadium and niobium. 
 
     
     
       12. The titanium alloy of  claim 9  comprising, in weight percentages based on total alloy weight:
 2.0 to 3.0 molybdenum. 
 
     
     
       13. The titanium alloy of  claim 9  comprising, in weight percentages based on total alloy weight:
 1.0 to 2.0 molybdenum. 
 
     
     
       14. The titanium alloy of  claim 9 , wherein the titanium alloy comprises an aluminum equivalent value of 7.0 to 8.0. 
     
     
       15. The titanium alloy of  claim 9 , wherein the titanium alloy comprises a molybdenum equivalent value of 6.0 to 7.0. 
     
     
       16. The titanium alloy of  claim 9 , wherein the titanium alloy comprises an aluminum equivalent value of 7.0 to 8.0 and a molybdenum equivalent value of 6.0 to 7.0. 
     
     
       17. The titanium alloy of  claim 16 , wherein the titanium alloy comprises, in weight percentages based on total alloy weight:
 8.6 to 9.4 of one or more elements selected from the group consisting of vanadium and niobium; 
 4.6 to 5.4 tin; 
 3.0 to 3.9 aluminum; 
 2.0 to 3.0 molybdenum; and 
 2.6 to 3.4 zirconium. 
 
     
     
       18. The titanium alloy of  claim 16 , wherein the titanium alloy comprises, in weight percentages based on total alloy weight:
 10.6 to 11.4 of one or more elements selected from the group consisting of vanadium and niobium; 
 6.6 to 7.4 tin; 
 2.0 to 3.4 aluminum; 
 1.0 to 2.0 molybdenum; and 
 1.6 to 2.4 zirconium. 
 
     
     
       19. The titanium alloy of  claim 9 , wherein the titanium alloy exhibits an ultimate tensile strength (UTS) of at least 170 ksi at room temperature, and wherein the ultimate tensile strength and an elongation of the titanium alloy satisfy the equation:
   (7.5×Elongation in %)+UTS≥260.5.
 
 
     
     
       20. A method of making a titanium alloy, the method comprising:
 solution treating a titanium alloy at 760° C. to 840° C. for 2 to 4 hours; 
 air cooling the titanium alloy to ambient temperature; 
 aging the titanium alloy at 482° C. to 593° C. for 8 to 16 hours; and 
 air cooling the titanium alloy, wherein the titanium alloy has the composition recited in  claim 9 . 
 
     
     
       21. A titanium alloy consisting essentially of, in weight percentages based on total alloy weight:
 2.0 to 5.0 aluminum; 
 greater than 3.0 to 8.0 tin; 
 1.0 to 5.0 zirconium; 
 0 to a total of 16.0 of one or more elements selected from the group consisting of oxygen, vanadium, molybdenum, niobium, chromium, iron, copper, and nitrogen; 
 0.001 to 0.07 carbon; 
 titanium; and 
 impurities. 
 
     
     
       22. The titanium alloy of  claim 21 , wherein a sum of vanadium and niobium contents in the alloy is, in weight percentages based on total alloy weight, 6.0 to 12.0. 
     
     
       23. The titanium alloy of  claim 21 , wherein a molybdenum content in the alloy is, in weight percentages based on total alloy weight, 0.1 to 5.0. 
     
     
       24. The titanium alloy of  claim 21 , wherein an aluminum equivalent value of the titanium alloy is 6.0 to 9.0. 
     
     
       25. The titanium alloy of  claim 21 , wherein a molybdenum equivalent value of the titanium alloy is 5.0 to 10.0. 
     
     
       26. The titanium alloy of  claim 21 , wherein an aluminum equivalent value of the titanium alloy is 6.0 to 9.0 and a molybdenum equivalent value of the titanium alloy is 5.0 to 10.0. 
     
     
       27. The titanium alloy of  claim 26 , wherein in the titanium alloy:
 a sum of vanadium and niobium contents is 6.0 to 12.0; 
 a molybdenum content is 0.1 to 5.0; 
 an iron content is 0.01 to 0.30; 
 an oxygen content is 0.005 to 0.3; and 
 a nitrogen content is 0.001 to 0.03, 
 all in weight percentages based on total weight of the titanium alloy. 
 
     
     
       28. The titanium alloy of  claim 27 , wherein a sum of aluminum, tin, and zirconium contents is, in weight percentages based on the total alloy weight, 8 to 15. 
     
     
       29. The titanium alloy of  claim 27 , wherein a ratio of the aluminum equivalent value to the molybdenum equivalent value of the titanium alloy is 0.6 to 1.3. 
     
     
       30. The titanium alloy of  claim 21 , wherein the titanium alloy exhibits an ultimate tensile strength (UTS) of at least 170 ksi at room temperature, and wherein the ultimate tensile strength and an elongation of the titanium alloy satisfy the equation:
   (7.5×Elongation in %)+UTS≥260.5.
 
 
     
     
       31. A method of making a titanium alloy, the method comprising:
 solution treating a titanium alloy at 760° C. to 840° C. for 2 to 4 hours; 
 air cooling the titanium alloy to ambient temperature; 
 aging the titanium alloy at 482° C. to 593° C. for 8 to 16 hours; and 
 air cooling the titanium alloy, wherein the titanium alloy has the composition recited in  claim 21 . 
 
     
     
       32. A method of making a titanium alloy, the method comprising:
 solution treating a titanium alloy at a temperature range from beta transus minus 10° C. to beta transus minus 100° C. for 2 to 4 hours; 
 air cooling or fan air cooling the titanium alloy to ambient temperature; 
 aging the titanium alloy at 482° C. to 593° C. for 8 to 16 hours; and 
 air cooling the titanium alloy, wherein the titanium alloy has the composition recited in  claim 21 . 
 
     
     
       33. A titanium alloy comprising, in weight percentages based on total alloy weight:
 2.0 to 5.0 aluminum; 
 3.0 to 8.0 tin; 
 1.0 to 5.0 zirconium; 
 8.6 to 11.4 vanadium; 
 0.1 to 5.0 molybdenum; 
 0.01 to 0.40 iron; 
 0.005 to 0.3 oxygen; 
 0.001 to 0.07 carbon; 
 0.001 to 0.03 nitrogen; 
 an aluminum equivalent value of 6.0 to 9.0; 
 a molybdenum equivalent value of 5.0 to 10.0; 
 optionally, one or more of niobium, chromium, and copper, wherein a total content of oxygen, molybdenum, niobium, chromium, iron, copper, nitrogen, and carbon is no greater than 16.0; 
 titanium; and 
 impurities.